""" 新数据结构，二叉搜索树 """
def lowestCommonAncestor(self, root: 'TreeNode', p: 'TreeNode', q: 'TreeNode') -> 'TreeNode':
        
    if p.val<root.val and q.val<root.val:
        return self.lowestCommonAncestor(root.left,p,q)
    
    if p.val>root.val and q.val>root.val:
        
        return self.lowestCommonAncestor(root.right,p,q)
    
    return root